Polyacrylamide gel electrophoresis is an analytical technique whereby fragments of biomolecules, such as DNA, enzymes and proteins, may be separated and identified on the basis of their molecular size, weight and charge. Commercially available electrophoresis gels have conventionally been produced by copolymerisation of acrylamide with the symmetrical crosslinking agent, N,N'-methylene bisacrylamide, otherwise known as BIS. Since both double bonds of BIS are of the same type their reactivities are essentially the same. Other known crosslinking agents include ethylene glycol diacrylate, dihydroxy ethylene-bisacrylamide (DHEBA), N,N'-propylenebisacrylamide, diacrylamide dimethylether, 1,2-diacrylamide ethyleneglycol, ethyleneureabisacrylamide, N,N'-bisacrylylcystamine and bisacrylamide methylether (BAME). As for BIS, the double bonds of these crosslinking agents are of the same type.